Fig. 6. Time course of sulfate in raw wastewater input and in drainage water from aerated lysimeters (AIR) and lysimeters vented to the leachfield (LEACH). The wastewater loading rate was changed from 12 to 4 cm d^–1 on 21 Apr. 2003. Values are means (n = 3). Bars represent one standard deviation. Significant differences between AIR and LEACH treatments (P < 0.05) for a particular sampling date are indicated with an asterisk (*).